Illustrated Glossary of Organic Chemistry - HOMO

Illustrated Glossary of Organic Chemistry

HOMO: Highest Occupied Molecular Orbital. The highest energy molecular orbital containing an electron pair.

	Label	Orbital	Occupancy
	π₄*		Unoccupied
	π₃*		Unoccupied	LUMO
	π₂			HOMO
	π₁

The pi molecular orbitals of 1,3-butadiene. This molecule has four pi electrons. In its ground state, π₁ and π₂ each contain two electrons, and π₃* and π₄* are unoccupied. π₂ is the HOMO and π₃* is the LUMO.

Related terms: SOMO, HOMO-LUMO gap, conjugation, orbital, s orbital, p orbital, p_x orbital, p_y orbital, p_z orbital, hybrid orbital, sp³ orbital, sp² orbital, sp orbital, bonding molecular orbital, nonbonding molecular orbital, antibonding molecular orbital, sigma orbital, σ orbital, sigma* orbital, σ* orbital, pi orbital, π orbital, pi* orbital, π* orbital, orbital electronegativity
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